1. Field of the Invention
The present invention relates generally to computer implemented simulation methods for ion implantation into semiconductor substrates, and more specifically to the generation of a mesh in a cross-section of a semiconductor substrate to define an orthogonal coordinate system.
2. Description of the Related Art
According to a known computer-implemented method for ion implantation simulation, a mesh is generated to define an orthogonal coordinate system in a vertical cross-section of a simulated semiconductor substrate. As described in "Handou-Tai Soshi Simulator (Semiconductor Device Simulator)", H. Koike et al., Fuji-Sougou Kenkyujo, Maruzen Publishing Company, Aug. 25, 1991, pages 115 and 116, the horizontal parallel lines of the mesh are drawn such that those immediately below the flat top surface of a silicon substrate are spaced narrower than those in a deeper region of the substrate. The vertical parallel lines of the mesh are drawn such that those near mask edges are spaced narrower than those inside the substrate since the impurity profile near the mask edges varies violently and so it must be defined with high resolution. Simulation of ion implantation is then performed and the meshed coordinate system is used to produce an impurity profile.
While satisfactory for low energy applications, the spacing of the horizontal parallel lines in the substrate's deeper region is too coarse to give a high definition of an impurity profile, particularly its peak region, when high energy is used for implantation of ions.